yb7hx with audio dungdung

Yaesu FT-2000

2009-01-15T16:35:00.003+08:00

The FT-2000 is the 2nd Generation in the proud lineage of the FTdx9000 Series! Featuring extensive DSP filtering, 100 Watts of power output, and a host of outstanding ergonomic and performance features, the FT-2000 is destined to be the centerpiece of your HF/50 MHz station!

160 - 6 Meter Coverage, 100 Watts of Power!

The FT-2000 provides a full 100 Watts of power output (AM: 25 W) on the 160-6 Meter Amateur bands, and the U.S. version includes a special memory bank containing the five 60-meter channels, as well. Continuous receiver coverage from 30 kHz to 60 MHz is provided. Note: frequency coverage may differ in your country.

Extensive Receiver DSP Filtering!

The power of IF Digital Signal Processing (DSP) is yours to enjoy with the FT-2000. Variable IF Width and IF Shift allow precise interference rejection, and the receiver DSP also includes an Auto-Notch, Manual Notch, Digital Noise Reduction, and a continuously-variable passband Contour control. The WIDTH control has a mode-determined adjustment range of 200 Hz – 4 kHz for SSB, and 25 Hz to 2.4 kHz on CW, and a mode-optimized “Narrow” key provides one-touch narrowing of the bandwidth to a user-determined preset value.

User-Adjustable Variable TX Bandwidth!

With the FT-2000, you have tremendous control over the fidelity and/or “talk power” of your SSB signal, thanks to the variable SSB bandwidth capability in the Menu. The default bandwidth is 2.4 kHz (300 – 2400 Hz @ -6 dB), but you also have selections of 50 – 3000 Hz, 100 – 2900 Hz, 200 – 2800 Hz, and 400 – 2600 Hz, allowing you to select the bandwidth best suiting your operating needs.

3-Band Parametric Microphone Equalizer!

The power of DSP also provides tremendous benefits for transmission, as well as reception. The Three-Band Parametric Microphone Equalizer allows unmatched capability to tailor your speech characteristics: in each of the three bands, you may adjust the center frequency of the equalization, the frequency spread over which the equalization is applied, and the amplitude (peaking or nulling) within that equalization range. The result is sparkling, clear audio that will be the envy of everyone else on the band!

Outstanding Strong-Signal-Handling Capabilities Derived from the FTDX9000!

Following in the renowned path of the FTDX9000, the FT-2000 is crafted with a comprehensive design view that accounts for all aspects of the strong signal environment, and especially with optimization of weak-signal in a multiple-strong-signal environment. The receiver of the FT-2000 is a triple-conversion type, utilizing great care in the gain distribution through all IF stages. The first mixer is a GaAs FET Doubly-Balanced Mixer type, fed by a four-VCO PLL synthesizer (30 kHz – 10.5 MHz, 10.5 MHz – 24 MHz, 24 MHz – 39 MHz, and 39 MHz – 56 MHz). The resulting first IF is at 69.450 MHz, utilizing an up-conversion technique that yields excellent image rejection.

FTDX9000-Lineage Triple Roofing Filter System for Crowded Bands (Main Band VFO)

The first IF of the FT-2000 features three roofing filters, I bandwidths of 15 kHz, 6 kHz, and 3 kHz, optimized by mode for best performance on today’s crowded bands. Especially useful during busy contest weekends, the Roofing Filters are positioned right after the first mixer, improving IP3 (3rd-Order Intercept Point) performance for all stages that follow.

The Ultimate Low-Band DXer RF Preselection Filter: YAESU’s Exclusive µ-Tuning!

On the lower Amateur bands, the signal voltages impinging on a receiver can create noise and Intermodulation effects that can cover up weak signals you’re trying to pull through. So YAESU’s engineers developed the µ (Mu) Tuning system for the FTDX9000, and it’s now available as an option for the FT-2000. Three modules are available (MTU-160, MTU-80/40, MTU-30/20), and these modules may be connected externally with no internal modification required! When µ-Tuning is engaged, the standard VRF (Variable RF Preselector) system is bypassed, but the fixed Bandpass Filters are still in the received signal path. The µ-Tuning filters utilize a stack of large 1.1” (28 mm) Ni-Zn Ferrite cores, driven through a silver-plated coil assembly by a precision stepper motor. The resulting high Q (typically over 300) provides a very steep resonance peak near your operating frequency. The peak may be adjusted away from your frequency, for even greater protection from a specific station, and a graphical depiction of the µ-Tune filter alignment appears on the front panel of the transceiver.

Unique Receiver Configuration Display

When operating at a frantic pace, it’s a comfort to have such comprehensive information available on the front panel’s huge display. The FT-2000’s unique "Receiver Configuration Display” calls out status for each step in the receiver’s RF and IF, and the fluorescent display also provides both graphical and numerical depiction of the bandwidth and the alignment of the various interference-rejection filters. And the high-resolution analog multi-meter allows you to monitor PO/COMP/SWR/ID/VDD/ALC both effortlessly and precisely.

Dual Receive Capability for Effortless Split Operation

During Split operation, Dual Receive may be engaged so that you may listen to both sides of the pile-up (or watch a particular frequency on the same band for activity). One push of the appropriate [TX] or [RX] indicator will engage or disengage the receiver or transmitter on the Main or Sub VFO, and the [TXW] (TX Watch) button also lets you listen to your transmit frequency during casual Split operation. The Sub Receiver also has a slot for an optional Collins® Mechanical CW filter, if desired: choose the YF-122C (500 Hz) or the YF-122CN (300 Hz). The Sub Receiver is an analog type, with no DSP filters.

Enhance Operation using External Display (option)!

A wide array of informative and useful displays, identical to those available on the FTDX9000D, can be obtained by adding the optional DMU-2000 Data Management Unit and an after-market display (not supplied). You get an Audio Scope (plus “Waterfall”) and Oscilloscope, Logging Page, Band Scope, World Clock with Sunrise/Sunset Terminator Display, Swept-frequency SWR display, Memory Channel listing, Rotator Control display with Great Circle Map, and a comprehensive Menu listing, as well. Enjoy the ultimate in operating ease by adding the DMU-2000!

Five-Group, 99-Channel memory with 5-Channel Quick Memory Bank (QMB)

The 99 memories may be organized into up to five memory groups (up to 20 channels each), and with the addition of the optional DMU-2000 Data Management Unit, you can connect your keyboard (not supplied) and add memory labels (names), edit data, and perform backup and other functions, as well, using an external computer monitor (not supplied). In addition, the one-touch Store (STO) and Recall (RCL) keys allow you instant access to a five-channel Quick Memory Bank that gives you access to five frequencies on a first-in, first-out running basis.

A Host of Features for the CW Enthusiast!

The front and rear panels have their own key jacks, which may be set up independently for connection of a keyer paddle (for use with the internal keyer), a straight key or bug, or a computer-driven keying interface for use with contest logging software, etc. With the FT-2000, you can use both your ears and your eyes to zero in on another CW station. The CW SPOT switch engages a spotting tone that matches the offset of your transmitted signal (as set by the CW Pitch selection), allowing you to match that pitch to that of an incoming signal perfectly. And the CW Tuning Indicator provides a graphical depiction of the tuning process, with a ? marker lighting up when the incoming signal is precisely aligned with yours.

Five-Channel Digital Voice Memory and 15-Second Digital RX Recorder

For storage and playback of repetitive messages you have to transmit in a contest, the four-channel Digital Voice Recorder (5 channels when using the optional FH-2 Keypad) will quickly and efficiently let you store CQ, Contest Number, and “QRZ” messages. On receive, a running 15-second loop recorder lets you stop the recording and play back the just-received audio, so you can confirm a callsign, for example.

Huge Precision Main Tuning Dual!

The front panel’s oversized 2.67” (68 mm) Main Tuning Knob is crafted using a brass JISC3604R alloy, for easy flywheel-effect frequency excursions or precision tuning of weak digital signals. The torque of the tuning knob shaft may be adjusted for just the amount of drag you prefer, and all it will take is one spin of the dial for you to know that you are in command of a serious radio!

Built-in 100-Memory Automatic Antenna Tuner

The 100 memories of matching-point data allow you to tune around the bands without the need to re-tune as you go. The special antenna tuner memories ensure efficient operation, as well as lightning-fast matching at new operating frequencies, as needed. The Automatic Antenna Tuner has a matching range of 16.7 to 150 Ohms (50 MHz: 25 - 100 Ohms).

Personal Computer Control Softwre Available for Free Download!

Just go to the "Files" tab in this area, and look for the "PCC-2000-E" Zip File. Download it for free, and enjoy your "virtual front panel" of the FT-2000 on your computer screen.

And Much, Much More. . .

Flexible Connection Points for RTTY, SSTV, PSK31, JT65 (EME) and other Digital Modes; VOX (Automatic voice-operated TX/RX control); All mode Squelch; FM Mode: 50-Tone CTCSS Encode/Decode System; Band-Specific Repeater Shifts for 29/50 MHz FM; Wide/Narrow modes for AM and FM; Flexible, easy-to-use VFO/Memory command selections: A>B, A=B, V/M, M>A, A>M; Memory Channel Offset Tuning (MT); Versatile Scanning Capability; Versatile Menu Mode for customization of setup and features; Transverter Jack; Constant-level rear-panel sound recording jack; Comprehensive external RS-232C computer control (CAT) protocol; Optional FH-2 Keypad provides ease of control for CW or Voice Messages and Receiver Loop recording.

source :http://www.yaesu.com

Heil Sound PR 40 Microphone

2009-01-15T10:10:00.000+08:00

The PR 40, with its broad frequency response, is the ideal mic for bass drums and bass guitar. With its superb rear rejection the PR 40 is a must for broadcasters.

Producing the widest frequency range available in a dynamic microphone, the PR 40 outperforms most condenser microphones, and can withstand huge amounts of SPL. At the same time, it maintains the 25 year Heil Sound tradition of superbly natural voice articulation.

Since 1982, Heil Sound has been the leading manufacturer of communications microphones and has a paramount understanding of phasing. When properly applied, this knowledge creates outstanding cardioid patterns with unbelievable rear rejection that removes unwanted sounds that try to enter from the off axis rear.

The pattern control of the Heil PR 40 is outstanding. This exceptional performance is achieved by using the ideal combination of materials for the large low mass diaphragm and a special mixture of neodymium, iron, and boron that gives the PR 40 the strongest magnet structure available. These features allow the microphone to achieve magnificent dynamic range.

A unique screen system using two different diameter mesh screens and an internal breath blast filter allow the user to talk closely to the microphone with little worry of pops or excessive sibilance.

The large diameter dynamic element is mounted in a unique Sorbothane © shock mount atop a non-resonant fixture, decoupling the element from the massive steel body.

This body and the internal hum bucking coil removes any worry of using the PR 40 near monitor screens or noisy lighting fixtures and controls.

The new technology of the Heil PR 40 has redefined the dynamic microphone with superior wide frequency response, the lowest presence of noise in the industry, flawless design, and elite quality expected by an innovator and leader in the field.

Welcome to the new standard.

Features:

* Absolute most natural voice response for talk show hosts, voice over applications
* Large low-mass aluminum voice coil
* Properly positioned hum bucking coil and heavy steel case insure maximum shielding
* Four rear ports exhibit excellent rear rejection and minimum proximity effect
* Widest frequency response
* Best kick drum microphone ever
* Assembled and tested in Illinois

Product Options:

* SM-2 Shock Mount
* CB-1 PTT Microphone Base
* PL2 Topless 'Mount'

Source : Broadcastwerehouse

Kenwood TS-2000/B2000/2000x

2009-01-11T02:16:00.000+08:00

TS-2000/B2000/2000X
HF/All-Mode Transceivers

The all new Kenwood TS-2000 series transceiver offers today's demanding Amateur operator high performance standards without the compromising limitations found in other similar multi-band, multi-mode transceiver. The TS-2000 offers users three distinct operation platforms, the traditional transceiver with full function front panel, or the high-tech looking "silver box" version that allows mobile operation with the new RC-2000 compact control head, or the ARCP-2000 computer control program making the TS-B2000 functional from your personal computer. The new TS-2000 offers 100 watts on HF, 6 meters and 2 meters, 50 watts on 70cm, and when you install the optional UT-20 1.2 GHz module at 10 watts, you will have assembled the most complete dual receiver multi-mode transceiver ever produced. The TS-2000 is transverter frequency display function ready to work with the latest satellite frequencies available.

General Features

• High performance true IF/stage DSP on main band. AF stage DSP on sub-band.
• Digital filtering. (No more expensive options to buy)
• Satellite ready, with transverter frequency display.
• Wide band receive.
• Dual receive, (HF & 2m or 70cm) (2m & 2m) (70cm & 70cm)
• Cross band repeat.
• 100 watts output on HF, 6 and 2 meters. 50 watts output on 70cm, 10 watts output on 1.2 GHz (optional UT-20)
• Built-in a Auto Tuner HF through 6 meters
• Built-in TNC for KSS/DX PACKET CLUSTER TUNE
• Built-in RS-232 for computer control
• Built-in TCXO (.5PPM)
• CTCSS & DCS encode/decode
• Electronic memory keyer World
• 5+1 Antenna ports. (2 for HF & 6m, 1 for 2m, 1 for 70cm, 1 for 1.2 GHz option & 1 for and HF receive antenna)

Specifications

Automatic Antenna Tuner	Yes
Beat Cancel	Yes
Cross Band Repeat	Yes
CTCSS	Enc/Dec
CW Auto Tune	Yes
DCS	Enc/Dec
Dual Band Receive	Yes
DX Packet Cluster Tune	Yes
Memory Channels	100
Noise Reduction	Yes
Number of Bands	13
PC Programmable	Yes
Radio Control Software	Yes ARCP-2000 (Optional)
Receiver Operating Mode	FM/FM-W/FM-N AM/USB/LSB/CW
Receiver Range	Main: (.03).5-30Mhz, (30)50-54(60)MHz, (142)144-148(152)MHz, (420)430-450MHz 1240-1300MHz (TS-2000X Only)Sub: (118) 144-148(174) MHz, (220) 438-450 (512) MHz *Figures in parenthesis () indicate VFO coverage range
RX Equalizer	Yes
Satellite Communications	Yes
SkyCommand	Yes
TNC	Yes
Transmit Frequency Range	50-54MHz
TX Equalizer	Yes
TX Monitor	Yes
Voice Synthesizer (Optional)	Yes VS-3
VoIP	No
Wide/Narrow FM	Yes

Source : http://www.kenwoodusa.com

Amateur radio

2009-01-10T20:15:00.000+08:00

Amateur radio, often called ham radio, is both a hobby and a service in which participants, called "hams," use various types of radio communications equipment to communicate with other radio amateurs for public service, recreation and self-training

Amateur radio operators enjoy personal (and often worldwide) wireless communications with each other and are able to support their communities with emergency and disaster communications if necessary, while increasing their personal knowledge of electronics and radio theory. An estimated six million people throughout the world are regularly involved with amateur radio.

The term "amateur" is not a reflection on the skills of the participants, which are often quite advanced; rather, "amateur" indicates that amateur radio communications are not allowed to be made for commercial or money-making purposes.

History

Though its origins can be traced to at least the late 1800s, amateur radio, as practiced today, did not begin until the early 1900s. The first listing of amateur radio stations is contained in the First Annual Official Wireless Blue Book of the Wireless Association of America in 1909. This first radio callbook lists wireless telegraph stations in Canada and the United States, including eighty-nine amateur radio stations. As with radio in general, the birth of amateur radio was strongly associated with various amateur experimenters and hobbyists. Throughout its history, amateur radio enthusiasts have made significant contributions to science, engineering, industry, and social services. Research by amateur radio operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency.

Activities and practices

Radio amateurs use various modes of transmission to communicate. Voice transmissions are most common, with some such as frequency modulation (FM) offering high quality audio, and others such as single sideband (SSB) offering more reliable communications when signals are marginal and bandwidth is restricted.

Radiotelegraphy using Morse code is an activity dating to the earliest days of radio. Technology has moved past the use of telegraphy in nearly all other communications, and a code test is no longer part of most national licensing exams for amateur radio. Many amateur radio operators continue to make use of the mode, particularly on the shortwave bands and for experimental work such as earth-moon-earth communication, with its inherent signal-to-noise ratio advantages. Morse, using internationally agreed code groups, also allows communications between amateurs who speak different languages. It is also popular with homebrewers as CW-only transmitters are simpler to construct. A similar "legacy" mode popular with home constructors is amplitude modulation (AM), pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology.

For many years, demonstrating a proficiency in Morse code was a requirement to obtain amateur licenses for the high frequency bands (frequencies below 30 MHz), but following changes in international regulations in 2003, countries are no longer required to demand proficiency. As an example, the United States Federal Communications Commission phased out this requirement for all license classes on February 23, 2007.

Modern personal computers have encouraged the use of digital modes such as radioteletype (RTTY), which previously required cumbersome mechanical equipment Hams led the development of packet radio, which has employed protocols such as TCP/IP since the 1970s. Specialized digital modes such as PSK31 allow real-time, low-power communications on the shortwave bands. Echolink using Voice over IP technology has enabled amateurs to communicate through local Internet-connected repeaters and radio nodes, while IRLP has allowed the linking of repeaters to provide greater coverage area. Automatic link establishment (ALE) has enabled continuous amateur radio networks to operate on the high frequency bands with global coverage. Other modes, such as FSK441 using software such as WSJT, are used for weak signal modes including meteor scatter and moonbounce communications.

Fast scan amateur television has gained popularity as hobbyists adapt inexpensive consumer video electronics like camcorders and video cards in home computers. Because of the wide bandwidth and stable signals required, amateur television is typically found in the 70 cm (420 MHz–450 MHz) frequency range, though there is also limited use on 33 cm (902 MHz–928 MHz), 23 cm (1240 MHz–1300 MHz) and higher. These requirements also effectively limit the signal range to between 20 and 60 miles (30 km–100 km), however, the use of linked repeater systems can allow transmissions across hundreds of miles.

These repeaters, or automated relay stations, are used on VHF and higher frequencies to increase signal range. Repeaters are usually located on top of a mountain, hill or tall building, and allow operators to communicate over hundreds of square miles using a low power hand-held transceiver. Repeaters can also be linked together by use of other amateur radio bands, landline or the Internet.

Communication satellites called OSCARs (Orbiting Satellite Carrying Amateur Radio) can be accessed, some using a hand-held transceiver (HT) with a stock "rubber duck" antenna. Hams also use the moon, the aurora borealis, and the ionized trails of meteors as reflectors of radio waves. Hams are also often able to make contact with the International Space Station (ISS), as many astronauts and cosmonauts are licensed as Amateur Radio Operators.

Amateur radio operators use their amateur radio station to make contacts with individual hams as well as participating in round table discussion groups or "rag chew sessions" on the air. Some join in regularly scheduled on-air meetings with other amateur radio operators, called "Nets" (as in "networks") which are moderated by a station referred to as "Net Control". Nets can allow operators to learn procedures for emergencies, be an informal round table or be topical, covering specific interests shared by a group.

Licensing

In all countries, amateur radio operators are required to pass a licensing exam displaying knowledge and understanding of key concepts. In response, hams are granted operating privileges in larger segments of the radio frequency spectrum using a wide variety of communication techniques with higher power levels permitted. This practice is in contrast to unlicensed personal radio services such as CB radio, Multi-Use Radio Service, or Family Radio Service/PMR446 that require type-approved equipment restricted in frequency range and power.

In many countries, amateur licensing is a routine civil administrative matter. Amateurs are required to pass an examination to demonstrate technical knowledge, operating competence and awareness of legal and regulatory requirements in order to avoid interference with other amateurs and other radio services. There are often a series of exams available, each progressively more challenging and granting more privileges in terms of frequency availability, power output, permitted experimentation, and in some countries, distinctive callsigns. Some countries such as the United Kingdom and Australia have begun requiring a practical training course in addition to the written exams in order to obtain a beginner's license, called a Foundation License.

Amateur radio licensing in the United States serves as an example of the way some countries award different levels of amateur radio licenses based on technical knowledge. Three sequential levels of licensing exams (Technician Class, General Class and Amateur Extra Class) are currently offered, which allow operators who pass them access to larger portions of the Amateur Radio spectrum and more desirable callsigns.

Newcomers

Many people start their involvement in amateur radio by finding a local club. Clubs often provide information about licensing, local operating practices and technical advice. Newcomers also often study independently by purchasing books or other materials, sometimes with the help of a mentor, teacher or friend. Established amateurs who help newcomers are often referred to as "Elmers" within the ham community. In addition, many countries have national amateur radio societies which encourage newcomers and work with government communications regulation authorities for the benefit of all radio amateurs. The oldest of these societies is the Wireless Institute of Australia, formed in 1910; other notable societies are the Radio Society of Great Britain, the American Radio Relay League, Radio Amateurs of Canada, the New Zealand Association of Radio Transmitters and South African Radio League. (See Category:Amateur radio organizations)

Callsigns

Upon licensing, a radio amateur's national government issues a unique callsign to the radio amateur. The holder of a callsign uses it on the air to legally identify the operator or station during any and all radio communication. In certain jurisdictions, an operator may also select a "vanity" callsign. Some jurisdictions, such as the U.S., require that a fee be paid to obtain such a vanity callsign; in others, such as the UK, a fee is not required and the vanity callsign may be selected when the license is applied for.

Callsign structure as prescribed by the ITU, consists of three parts which break down as follows, using the callsign ZS1NAT as an example:

1. ZS – Shows the country from which the callsign originates and may also indicate the license class. (This callsign is licensed in South Africa, and is CEPT Class 1).
2. 1 – Tells you the subdivision of the country or territory indicated in the first part (this one refers to the Western Cape).
3. NAT – The final part is specific to the holder of the license, identifying that person specifically.

Many countries do not follow the ITU convention for the numeral. The United Kingdom never has - the calls G2xxx, G3xxx, and G6xx may be right next to each other. In the United States, the numeral indicated the geographical district until recently. Now, under FCC "deregulation", the numeral no longer can be relied upon to show where the licensee is located. Also, for smaller entities, the numeral may be part of the country identification. For example, VP2xxx is in the British West Indies (subdivided into VP2Exx Anguilla, VP2Mxx Monserrat, and VP2Vxx British Virgin Islands), VP5xxx is in the Turks and Caicos Islands, VP6xxx is on Pitcairn Island, VP8xxx is in the Falklands, and VP9xxx is in Bermuda.

Privileges

Unlike all other spectrum users, radio amateurs are allowed to build or modify transmitting equipment, and do not need to obtain type-approval for it. Licensed amateurs can also use any frequency in their bands (rather than being allocated fixed frequencies or channels) and can operate medium to high-powered equipment on a wide range of frequencies so long as they meet spurious emission standards.

As noted, radio amateurs have access to frequency allocations throughout the RF spectrum, enabling choice of frequency to enable effective communication whether across a city, a region, a country, a continent or the whole world regardless of season or time day or night. The shortwave bands, or HF, can allow worldwide communication, the VHF and UHF bands offer excellent regional communication, and the broad microwave bands have enough space, or bandwidth, for television (known as SSTV and FSTV) transmissions and high-speed data networks.
The international symbol for amateur radio, included in the logos of many IARU member societies. The diamond holds a circuit diagram featuring components common to every radio: an antenna, inductor and ground.

Although allowable power levels are moderate by commercial standards, they are sufficient to enable global communication. Power limits vary from country to country and between license classes within a country. For example, the power limits for the highest available license classes in a few selected countries are: 2.25 kW in Canada, was 2 kW in the former Yugoslavia, 1.5 kW in the United States, 1 kW in Belgium and Switzerland, 750 W in Germany, 500 W in Italy, 400 W in Australia, India and the United Kingdom, and 150 W in Oman. Lower license classes usually have lower power limits; for example, the lowest license class in the UK has a limit of just 10 W. Amateur radio operators are encouraged both by regulations and tradition of respectful use of the spectrum to use as little power as possible to accomplish the communication.

When traveling abroad, visiting amateur operators must follow the rules of the country in which they wish to operate. Some countries have reciprocal international operating agreements allowing hams from other countries to operate within their borders with just their home country license. Other host countries require that the visiting ham apply for a formal permit, or even a new host country-issued license, in advance.

Many jurisdictions issue speciality vehicle registration plates to amateur radio operators who provide proof of an amateur radio license. The fees for application and renewal are usually less than standard plates.

Band plans and frequency allocations

The International Telecommunication Union (ITU) governs the allocation of communications frequencies worldwide, with participation by each nation's communications regulation authority. National communications regulators have some liberty to restrict access to these frequencies or to award additional allocations as long as radio services in other countries do not suffer interference. In some countries, specific emission types are restricted to certain parts of the radio spectrum, and in most other countries, International Amateur Radio Union (IARU) member societies adopt voluntary plans to ensure the most effective use of spectrum.

In a few cases, a national telecommunication agency may also allow hams to use frequencies outside of the internationally allocated amateur radio bands. In Trinidad and Tobago, hams are allowed to use a repeater which is located on 148.800 MHz. This repeater is used and maintained by the National Emergency Management Agency (NEMA), but may be used by radio amateurs in times of emergency or during normal times to test their capability and conduct emergency drills. This repeater can also be used by non-ham NEMA staff and REACT members. In Australia and New Zealand ham operators are authorized to use one of the UHF TV channels. In the U.S., in cases of emergency, amateur radio operators may use any frequency including those of other radio services such as police and fire communications and the Alaska statewide emergency frequency of 5167.5 kHz.

Similarly, amateurs in the United States may apply to be registered with the Military Affiliate Radio System (MARS). Once approved and trained, these amateurs also operate on US Government Military frequencies to provide contingency communications and morale message traffic support to the military services.

Antenna (radio)

2008-08-29T09:01:00.000+08:00

Short Wave "Curtain" Antenna (Moosbrunn, Austria)

An antenna is a transducer designed to transmit or receive electromagnetic waves. In other words, antennas convert electromagnetic waves into electrical currents and vice versa. Antennas are used in systems such as radio and television broadcasting, point-to-point radio communication, wireless LAN, radar, and space exploration. Antennas usually work in air or outer space, but can also be operated under water or even through soil and rock at certain frequencies for short distances.

Physically, an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current, or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals. Some antenna devices (parabolic antenna, Horn Antenna) just adapt the free space to another type of antenna.

Thomas Edison used antennas by 1885. Edison patented his system in U.S. Patent 465,971 . Antennas were also used in 1888 by Heinrich Hertz (1857-1894) to prove the existence of electromagnetic waves predicted by the theory of James Clerk Maxwell. Hertz placed the emitter dipole in the focal point of a parabolic reflector. He published his work and installation drawings in Annalen der Physik und Chemie (vol. 36, 1889).

Terminology

The words antenna (plural: antennas^[1]) and "aerial" are used interchangeably; but usually a rigid metallic structure is termed an antenna and a wire format is called an aerial. In the United Kingdom and other British English speaking areas the term aerial is more common, even for rigid types. The noun aerial is occasionally written with a diaresis mark — aërial — in recognition of the original spelling of the adjective aërial from which the noun is derived.

The origin of the word antenna relative to wireless apparatus is attributed to Guglielmo Marconi. In 1895, while testing early radio apparatus in the Swiss Alps at Salvan, Switzerland in the Mont Blanc region, Marconi experimented with early wireless equipment. A 2.5 meter long pole, along which was carried a wire, was used as a radiating and receiving aerial element. In Italian a tent pole is known as l'antenna centrale, and the pole with a wire alongside it used as an aerial was simply called l'antenna. Until then wireless radiating transmitting and receiving elements were known simply as aerials or terminals. Marconi's use of the word antenna (Italian for pole) would become a popular term for what today is uniformly known as the antenna.^[2]

A Hertzian antenna is a set of terminals that does not require the presence of a ground for its operation (versus a Tesla antenna which is grounded. ^[3]) A loaded antenna is an active antenna having an elongated portion of appreciable electrical length and having additional inductance or capacitance directly in series or shunt with the elongated portion so as to modify the standing wave pattern existing along the portion or to change the effective electrical length of the portion. An antenna grounding structure is a structure for establishing a reference potential level for operating the active antenna. It can be any structure closely associated with (or acting as) the ground which is connected to the terminal of the signal receiver or source opposing the active antenna terminal (i.e., the signal receiver or source is interposed between the active antenna and this structure).

Overview

Antennas have practical uses for the transmission and reception of radio frequency signals (radio, TV, etc.). In air, those signals travel very quickly and with a very low transmission loss. The signals are absorbed when moving through more conducting materials, such as concrete walls, rock, etc. When encountering an interface, the waves are partially reflected

and partially transmitted through.

A common antenna is a vertical rod a quarter of a wavelength long. Such antennas are simple in construction, usually inexpensive, and both radiate in and receive from all horizontal directions (omnidirectional). One limitation of this antenna is that it does not radiate or receive in the direction in which the rod points. This region is called the antenna blind cone or null.

There are two fundamental types of antenna directional patterns, which, with reference to a specific three dimensional (usually horizontal or vertical) plane are either:

Omni-directional (radiates equally in all directions), such as a vertical rod or
Directional (radiates more in one direction than in the other).

In colloquial usage "omni-directional" usually refers to all horizontal directions with reception above and below the antenna being reduced in favor of better reception (and thus range) near the horizon. A "directional" antenna usually refers to one focusing a narrow beam in a single specific direction such as a telescope or satellite dish, or, at least, focusing in a sector such as a 120° horizontal fan pattern in the case of a panel antenna at a Cell site.

All antennas radiate some energy in all directions in free space but careful construction results in substantial transmission of energy in a preferred direction and negligible energy radiated in other directions. By adding additional elements (such as rods, loops or plates) and carefully arranging their length, spacing, and orientation, an antenna with desired directional properties can be created.

An antenna array is two or more simple antennas combined to produce a specific directional radiation pattern. In common usage an array is composed of active elements, such as a linear array of parallel dipoles fed as a "broadside array". A slightly different feed method could cause this same array of dipoles to radiate as an "end-fire array". Antenna arrays may be built up from any basic antenna type, such as dipoles, loops or slots.

The directionality of the array is due to the spatial relationships and the electrical feed relationships between individual antennas. Usually all of the elements are active (electrically fed) as in the log-periodic dipole array which offers modest gain and broad bandwidth and is traditionally used for television reception. Alternatively, a superficially similar dipole array, the Yagi-Uda Antenna (often abbreviated to "Yagi"), has only one active dipole element in a chain of parasitic dipole elements, and a very different performance with high gain over a narrow bandwidth.

An active element is electrically connected to the antenna terminals leading to the receiver or transmitter, as opposed to a parasitic element that modifies the antenna pattern without being connected directly. The active element(s) couple energy between the electromagnetic wave and the antenna terminals, thus any functioning antenna has at least one active element.

An antenna lead-in is the medium, for example, a transmission line or feed line for conveying the signal energy between the signal source or receiver and the antenna. The antenna feed refers to the components between the antenna and an amplifier.

An antenna counterpoise is a structure of conductive material most closely associated with ground that may be insulated from or capacitively coupled to the natural ground. It aids in the function of the natural ground, particularly where variations (or limitations) of the characteristics of the natural ground interfere with its proper function. Such structures are usually connected to the terminal of a receiver or source opposite to the antenna terminal.

An antenna component is a portion of the antenna performing a distinct function and limited for use in an antenna, as for example, a reflector, director, or active antenna.

Parasitic elements have no direct electrical connection to the antenna terminals, yet they modify the antenna pattern. The parasitic elements are immersed in the electromagnetic waves and fields around the active elements, and the parasitic currents induced in them interact with the original waves and fields. A careful arrangement of parasitic elements, such as rods or coils, can improve the radiation pattern of the active element(s). Directors and reflectors are common parasitic elements.

An electromagnetic wave refractor is a structure which is shaped or positioned to delay or accelerate transmitted electromagnetic waves, passing through such structure, an amount which varies over the wave front. The refractor alters the direction of propagation of the waves emitted from the structure with respect to the waves impinging on the structure. It can alternatively bring the wave to a focus or alter the wave front in other ways, such as to convert a spherical wave front to a planar wave front (or vice-versa). The velocity of the waves radiated have a component which is in the same direction (director) or in the opposite direction (reflector) as that of the velocity of the impinging wave.

A director is a parasitic element, usually a metallic conductive structure, which re-radiates into free space impinging electromagnetic radiation coming from or going to the active antenna, the velocity of the re-radiated wave having a component in the direction of the velocity of the impinging wave. The director modifies the radiation pattern of the active antenna but there is no direct electrical connection between the active antenna and this parasitic element.

A reflector is a parasitic element, usually a metallic conductive structure (e.g., screen, rod or plate), which re-radiates back into free space impinging electromagnetic radiation coming from or going to the active antenna. The velocity of the returned wave having a component in a direction opposite to the direction of the velocity of the impinging wave. The reflector modifies the radiation of the active antenna. There is no direct electrical connection between the active antenna and this parasitic element.

An antenna coupling network is a passive network (which may be any combination of a resistive, inductive or capacitive circuit(s)) for transmitting the signal energy between the active antenna and a source (or receiver) of such signal energy.

Typically, antennas are designed to operate in a relatively narrow frequency range. The design criteria for receiving and transmitting antennas differ slightly, but generally an antenna can receive and transmit equally well. This property is called reciprocity.

Parameters

Main article: Antenna measurement

There are several critical parameters affecting an antenna's performance that can be adjusted during the design process. These are resonant frequency, impedance, gain, aperture or radiation pattern, polarization, efficiency and bandwidth. Transmit antennas may also have a maximum power rating, and receive antennas differ in their noise rejection properties. All of these parameters can be measured through various means.

Resonant frequency

The "resonant frequency" and "electrical resonance" is related to the electrical length of an antenna. The electrical length is usually the physical length of the wire divided by its velocity factor (the ratio of the speed of wave propagation in the wire to c₀, the speed of light in a vacuum). Typically an antenna is tuned for a specific frequency, and is effective for a range of frequencies that are usually centered on that resonant frequency. However, other properties of an antenna change with frequency, in particular the radiation pattern and impedance, so the antenna's resonant frequency may merely be close to the center frequency of these other more important properties.

Antennas can be made resonant on harmonic frequencies with lengths that are fractions of the target wavelength. Some antenna designs have multiple resonant frequencies, and some are relatively effective over a very broad range of frequencies. The most commonly known type of wide band aerial is the logarithmic or log periodic, but its gain is usually much lower than that of a specific or narrower band aerial.

Gain

Main article: Antenna gain

Gain as a parameter measures the directionality of a given antenna. An antenna with a low gain emits radiation with about the same power in all directions, whereas a high-gain antenna will preferentially radiate in particular directions. Specifically, the Gain, Directive gain or Power gain of an antenna is defined as the ratio of the intensity (power per unit surface) radiated by the antenna in a given direction at an arbitrary distance divided by the intensity radiated at the same distance by a hypothetical isotropic antenna.

The gain of an antenna is a passive phenomenon - power is not added by the antenna, but simply redistributed to provide more radiated power in a certain direction than would be transmitted by an isotropic antenna. If an antenna has a greater than one gain in some directions, it must have a less than one gain in other directions since energy is conserved by the antenna. An antenna designer must take into account the application for the antenna when determining the gain. High-gain antennas have the advantage of longer range and better signal quality, but must be aimed carefully in a particular direction. Low-gain antennas have shorter range, but the orientation of the antenna is inconsequential. For example, a dish antenna on a spacecraft is a high-gain device that must be pointed at the planet to be effective, whereas a typical Wi-Fi antenna in a laptop computer is low-gain, and as long as the base station is within range, the antenna can be in an any orientation in space. It makes sense to improve horizontal range at the expense of reception above or below the antenna. Thus most antennas labelled "omnidirectional" really have some gain.^[4]

Sometimes, the half-wave dipole is taken as a reference instead of the isotropic radiator. The gain is then given in dBd (decibels over dipole):

0 dBd = 2.15 dBi

Radiation pattern

The radiation pattern of an antenna is the geometric pattern of the relative field strengths of the field emitted by the antenna. For the ideal isotropic antenna, this would be a sphere. For a typical dipole, this would be a toroid. The radiation pattern of an antenna is typically represented by a three dimensional graph, or polar plots of the horizontal and vertical cross sections. The graph should show sidelobes and backlobes, where the antenna's gain is at a minima or maxima.

See Antenna measurement: Radiation pattern or Radiation pattern for more information.

Impedance

As an electro-magnetic wave travels through the different parts of the antenna system (radio, feed line, antenna, free space) it may encounter differences in impedance (E/H, V/I, etc). At each interface, depending on the impedance match, some fraction of the wave's energy will reflect back to the source^[5], forming a standing wave in the feed line. The ratio of maximum power to minimum power in the wave can be measured and is called the standing wave ratio (SWR). A SWR of 1:1 is ideal. A SWR of 1.5:1 is considered to be marginally acceptable in low power applications where power loss is more critical, although an SWR as high as 6:1 may still be usable with the right equipment. Minimizing impedance differences at each interface (impedance matching) will reduce SWR and maximize power transfer through each part of the antenna system.

Complex impedance of an antenna is related to the electrical length of the antenna at the wavelength in use. The impedance of an antenna can be matched to the feed line and radio by adjusting the impedance of the feed line, using the feed line as an impedance transformer. More commonly, the impedance is adjusted at the load (see below) with an antenna tuner, a balun, a matching transformer, matching networks composed of inductors and capacitors, or matching sections such as the gamma match.

Efficiency

Efficiency is the ratio of power actually radiated to the power put into the antenna terminals. A dummy load may have an SWR of 1:1 but an efficiency of 0, as it absorbs all power and radiates heat but not RF energy, showing that SWR alone is not an effective measure of an antenna's efficiency. Radiation in an antenna is caused by radiation resistance which can only be measured as part of total resistance including loss resistance. Loss resistance usually results in heat generation rather than radiation, and reduces efficiency. Mathematically, efficiency is calculated as radiation resistance divided by total resistance.

Bandwidth

The bandwidth of an antenna is the range of frequencies over which it is effective, usually centered on the resonant frequency. The bandwidth of an antenna may be increased by several techniques, including using thicker wires, replacing wires with cages to simulate a thicker wire, tapering antenna components (like in a feed horn), and combining multiple antennas into a single assembly and allowing the natural impedance to select the correct antenna. Small antennas are usually preferred for convenience, but there is a fundamental limit relating bandwidth, size and efficiency.

Polarization

The polarization of an antenna is the orientation of the electric field (E-plane) of the radio wave with respect to the Earth's surface and is determined by the physical structure of the antenna and by its orientation. It has nothing in common with antenna directionality terms: "horizontal", "vertical" and "circular". Thus, a simple straight wire antenna will have one polarization when mounted vertically, and a different polarization when mounted horizontally. "Electromagnetic wave polarization filters" are structures which can be employed to act directly on the electromagnetic wave to filter out wave energy of an undesired polarization and to pass wave energy of a desired polarization.

Reflections generally affect polarization. For radio waves the most important reflector is the ionosphere - signals which reflect from it will have their polarization changed unpredictably. For signals which are reflected by the ionosphere, polarization cannot be relied upon. For line-of-sight communications for which polarization can be relied upon, it can make a large difference in signal quality to have the transmitter and receiver using the same polarization; many tens of dB difference are commonly seen and this is more than enough to make the difference between reasonable communication and a broken link.

Polarization is largely predictable from antenna construction but, especially in directional antennas, the polarization of side lobes can be quite different from that of the main propagation lobe. For radio antennas, polarization corresponds to the orientation of the radiating element in an antenna. A vertical omnidirectional WiFi antenna will have vertical polarization (the most common type). An exception is a class of elongated waveguide antennas in which vertically placed antennas are horizontally polarized. Many commercial antennas are marked as to the polarization of their emitted signals.

Polarization is the sum of the E-plane orientations over time projected onto an imaginary plane perpendicular to the direction of motion of the radio wave. In the most general case, polarization is elliptical (the projection is oblong), meaning that the antenna varies over time in the polarization of the radio waves it is emitting. Two special cases are linear polarization (the ellipse collapses into a line) and circular polarization (in which the ellipse varies maximally). In linear polarization the antenna compels the electric field of the emitted radio wave to a particular orientation. Depending on the orientation of the antenna mounting, the usual linear cases are horizontal and vertical polarization. In circular polarization, the antenna continuously varies the electric field of the radio wave through all possible values of its orientation with regard to the Earth's surface. Circular polarizations, like elliptical ones, are classified as right-hand polarized or left-hand polarized using a "thumb in the direction of the propagation" rule. Optical researchers use the same rule of thumb, but pointing it in the direction of the emitter, not in the direction of propagation, and so are opposite to radio engineers' use.

In practice, regardless of confusing terminology, it is important that linearly polarized antennas be matched, lest the received signal strength be greatly reduced. So horizontal should be used with horizontal and vertical with vertical. Intermediate matchings will lose some signal strength, but not as much as a complete mismatch. Transmitters mounted on vehicles with large motional freedom commonly use circularly polarized antennas so that there will never be a complete mismatch with signals from other sources. In the case of radar, this is often reflections from rain drops.

Transmission and reception

All of the antenna parameters are expressed in terms of a transmission antenna, but are identically applicable to a receiving antenna, due to reciprocity. Impedance, however, is not applied in an obvious way; for impedance, the impedance at the load (where the power is consumed) is most critical. For a transmitting antenna, this is the antenna itself. For a receiving antenna, this is at the (radio) receiver rather than at the antenna. Tuning is done by adjusting the length of an electrically long linear antenna to alter the electrical resonance of the antenna.

Antenna tuning is done by adjusting an inductance or capacitance combined with the active antenna (but distinct and separate from the active antenna). The inductance or capacitance provides the reactance which combines with the inherent reactance of the active antenna to establish a resonance in a circuit including the active antenna. The established resonance being at a frequency other than the natural electrical resonant frequency of the active antenna. Adjustment of the inductance or capacitance changes this resonance.

Antennas used for transmission have a maximum power rating, beyond which heating, arcing or sparking may occur in the components, which may cause them to be damaged or destroyed. Raising this maximum power rating usually requires larger and heavier components, which may require larger and heavier supporting structures. This is a concern only for transmitting antennas, as the power received by an antenna rarely exceeds the microwatt range.

Antennas designed specifically for reception might be optimized for noise rejection capabilities. An antenna shield is a conductive or low reluctance structure (such as a wire, plate or grid) which is adapted to be placed in the vicinity of an antenna to reduce, as by dissipation through a resistance or by conduction to ground, undesired electromagnetic radiation, or electric or magnetic fields, which are directed toward the active antenna from an external source or which emanate from the active antenna. Other methods to optimize for noise rejection can be done by selecting a narrow bandwidth so that noise from other frequencies is rejected, or selecting a specific radiation pattern to reject noise from a specific direction, or by selecting a polarization different from the noise polarization, or by selecting an antenna that favors either the electric or magnetic field.

For instance, an antenna to be used for reception of low frequencies (below about ten megahertz) will be subject to both man-made noise from motors and other machinery, and from natural sources such as lightning. Successfully rejecting these forms of noise is an important antenna feature. A small coil of wire with many turns is more able to reject such noise than a vertical antenna. However, the vertical will radiate much more effectively on transmit, where extraneous signals are not a concern.

Basic antenna models

There are many variations of antennas. Below are a few basic models. More can be found in Category:Radio frequency antenna types.

The isotropic radiator is a purely theoretical antenna that radiates equally in all directions. It is considered to be a point in space with no dimensions and no mass. This antenna cannot physically exist, but is useful as a theoretical model for comparison with all other antennas. Most antennas' gains are measured with reference to an isotropic radiator, and are rated in dBi (decibels with respect to an isotropic radiator).
The dipole antenna is simply two wires pointed in opposite directions arranged either horizontally or vertically, with one end of each wire connected to the radio and the other end hanging free in space. Since this is the simplest practical antenna, it is also used as a reference model for other antennas; gain with respect to a dipole is labeled as dBd. Generally, the dipole is considered to be omnidirectional in the plane perpendicular to the axis of the antenna, but it has deep nulls in the directions of the axis. Variations of the dipole include the folded dipole, the half wave antenna, the ground plane antenna, the whip, and the J-pole.
The Yagi-Uda antenna is a directional variation of the dipole with parasitic elements added with functionality similar to adding a reflector and lenses (directors) to focus a filament light bulb.
The random wire antenna is simply a very long (at least one quarter wavelength) wire with one end connected to the radio and the other in free space, arranged in any way most convenient for the space available. Folding will reduce effectiveness and make theoretical analysis extremely difficult. (The added length helps more than the folding typically hurts.) Typically, a random wire antenna will also require an antenna tuner, as it might have a random impedance that varies nonlinearly with frequency.
The Horn is used where high gain is needed, the wavelength is short (microwave) and space is not an issue. Horns can be narrow band or wide band, depending on their shape. A horn can be built for any frequency, but horns for lower frequencies are typically impractical. Horns are also frequently used as reference antennas.
The Patch antenna consists mainly of a square conductor mounted over a groundplane. An other example of a planar antenna is the Tapered Slot Antenna (TSA), as the Vivaldi-antenna.

Practical antennas

Although any circuit can radiate if driven with a signal of high enough frequency, most practical antennas are specially designed to radiate efficiently at a particular frequency. An example of an inefficient antenna is the simple Hertzian dipole antenna, which radiates over wide range of frequencies and is useful for its small size. A more efficient variation of this is the half-wave dipole, which radiates with high efficiency when the signal wavelength is twice the electrical length of the antenna.

One of the goals of antenna design is to minimize the reactance of the device so that it appears as a resistive load. An "antenna inherent reactance" includes not only the distributed reactance of the active antenna but also the natural reactance due to its location and surroundings (as for example, the capacity relation inherent in the position of the active antenna relative to ground). Reactance diverts energy into the reactive field, which causes unwanted currents that heat the antenna and associated wiring, thereby wasting energy without contributing to the radiated output. Reactance can be eliminated by operating the antenna at its resonant frequency, when its capacitive and inductive reactances are equal and opposite, resulting in a net zero reactive current. If this is not possible, compensating inductors or capacitors can instead be added to the antenna to cancel its reactance as far as the source is concerned.

Once the reactance has been eliminated, what remains is a pure resistance, which is the sum of two parts: the ohmic resistance of the conductors, and the radiation resistance. Power absorbed by the ohmic resistance becomes waste heat, and that absorbed by the radiation resistance becomes radiated electromagnetic energy. The greater the ratio of radiation resistance to ohmic resistance, the more efficient the antenna.

Effect of ground

Antennas are typically used in an environment where other objects are present that may have an effect on their performance. Height above ground has a very significant effect on the radiation pattern of some antenna types.

At frequencies used in antennas, the ground behaves mainly as a dielectric. The conductivity of ground at these frequencies is negligible. When an electromagnetic wave arrives at the surface of an object, two waves are created: one enters the dielectric and the other is reflected. If the object is a conductor, the transmitted wave is negligible and the reflected wave has almost the same amplitude as the incident one. When the object is a dielectric, the fraction reflected depends (among others things) on the angle of incidence. When the angle of incidence is small (that is, the wave arrives almost perpendicularly) most of the energy traverses the surface and very little is reflected. When the angle of incidence is near 90° (grazing incidence) almost all the wave is reflected.

Most of the electromagnetic waves emitted by an antenna to the ground below the antenna at moderate (say <>

The wave reflected by earth can be considered as emitted by the image antenna

This means that the receptor "sees" the real antenna and, under the ground, the image of the antenna reflected by the ground. If the ground has irregularities, the image will appear fuzzy.

If the receiver is placed at some height above the ground, waves reflected by ground will travel a little longer distance to arrive to the receiver than direct waves. The distance will be the same only if the receiver is close to ground.

In the drawing at right, we have drawn the angle far bigger than in reality. Distance between the antenna and its image is .

The situation is a bit more complex because the reflection of electromagnetic waves depends on the polarization of the incident wave. As the refractive index of the ground (average value ) is bigger than the refractive index of the air (), the direction of the component of the electric field parallel to the ground inverses at the reflection. This is equivalent to a phase shift of radians or 180°. The vertical component of the electric field reflects without changing direction. This sign inversion of the parallel component and the non-inversion of the perpendicular component would also happen if the ground were a good electrical conductor.

The vertical component of the current reflects without changing sign. The horizontal component reverses sign at reflection.

This means that a receiving antenna "sees" the image antenna with the current in the same direction if the antenna is vertical or with the current inverted if the antenna is horizontal.

For a vertical polarized emission antenna the far electric field of the electromagnetic wave produced by the direct ray plus the reflected ray is:

The sign inversion for the parallel field case just changes a cosine to a sine:

In these two equations:

is the electrical field radiated by the antenna if there were no ground.
is the wave number.
is the wave length.
is the distance between antenna and its image (twice the height of the center of the antenna).

Radiation patterns of antennas and their images reflected by the ground. At left the polarization is vertical and there is always a maximum for . If the polarization is horizontal as at right, there is always a zero for .

For emitting and receiving antenna situated near the ground (in a building or on a mast) far from each other, distances traveled by direct and reflected rays are nearly the same. There is no induced phase shift. If the emission is polarized vertically the two fields (direct and reflected) add and there is maximum of received signal. If the emission is polarized horizontally the two signals subtracts and the received signal is minimum. This is depicted in the image at right. In the case of vertical polarization, there is always a maximum at earth level (left pattern). For horizontal polarization, there is always a minimum at earth level. Note that in these drawings the ground is considered as a perfect mirror, even for low angles of incidence. In these drawings the distance between the antenna and its image is just a few wavelengths. For greater distances, the number of lobes increases.

Note that the situation is different – and more complex – if reflections in the ionosphere occur. This happens over very long distances (thousands of kilometers). There is not a direct ray but several reflected rays that add with different phase shifts.

This is the reason why almost all public address radio emissions have vertical polarization. As public users are near ground, horizontal polarized emissions would be poorly received. Observe household and automobile radio receivers. They all have vertical antennas or horizontal ferrite antennas for vertical polarized emissions. In cases where the receiving antenna must work in any position, as in mobile phones, the emitter and receivers in base stations use circular polarized electromagnetic waves.

Classical (analog) television emissions are an exception. They are almost always horizontally polarized, because the presence of buildings makes it unlikely that a good emitter antenna image will appear. However, these same buildings reflect the electromagnetic waves and can create ghost images. Using horizontal polarization, reflections are attenuated because of the low reflection of electromagnetic waves whose magnetic field is parallel to the dielectric surface near the Brewster's angle. Vertically polarized analog television has been used in some rural areas. In digital terrestrial television reflections are less annoying because of the type of modulation.

Mutual impedance and interaction between antennas

Mutual impedance between parallel dipoles not staggered. Curves Re and Im are the resistive and reactive parts of the impedance.

Current circulating in any antenna induces currents in all others. One can postulate a mutual impedance between two antennas that has the same significance as the in ordinary coupled inductors. The mutual impedance between two antennas is defined as:

where is the current flowing in antenna 1 and is the voltage that would have to be applied to antenna 2 – with antenna 1 removed – to produce the current in the antenna 2 that was produced by antenna 1.

From this definition, the currents and voltages applied in a set of coupled antennas are:

where:

is the voltage applied to the antenna $i$
is the impedance of antenna $i$
is the mutual impedance between antennas $i$ and $j$

Note that, as is the case for mutual inductances,

If some of the elements are not fed (there is a short circuit instead a feeder cable), as is the case in television antennas (Yagi-Uda antennas), the corresponding are zero. Those elements are called parasitic elements. Parasitic elements are unpowered elements that either reflect or absorb and reradiate RF energy.

In some geometrical settings, the mutual impedance between antennas can be zero. This is the case for crossed dipoles used in circular polarization antennas.

Antenna gallery

Antennas and antenna arrays

A Yagi-Uda beam antenna.	A multi-band rotary directional antenna for amateur radio use.	Rooftop television antenna. It is actually three Yagi antennas in one. The longest elements are for the low band (channels 2-6 (1-6 in the UK)) the medium-length elements are for the high band (channels 7-13) and the shortest elements are for the UHF band (channels 14-69 (21-68 in the UK)).	A terrestrial microwave radio antenna array.
Examples of US 136-174 MHz base station antennas.	Low cost LF time signal receiver, antenna (left) and receiver (right).	Rotatable log-periodic array for VHF and UHF.

Antennas and supporting structures

A building rooftop supporting numerous dish and sectored mobile telecommunications antennas (Doncaster, Victoria, Australia.

A three-sector telephone site in Mexico City.

Telephone site concealed as a palm tree.

Diagrams as part of a system

Antennas may be connected through a multiplexing arrangement in some applications like this trunked two-way radio example.

Antenna network for an emergency medical services base station.

[

Jeep Liberty

2008-08-21T06:52:00.000+08:00



Manufacturer	DaimlerChrysler (2002-07) Chrysler LLC (2008-present)
Production	2002-present
Assembly	Toledo, Ohio Cairo, Egypt Valencia, Carabobo, Venezuela
Predecessor	Jeep Cherokee
Class	Compact SUV
Body style(s)	4-door SUV
Layout	Front-engine, Rear-wheel drive / Four-wheel drive
Related	Dodge Nitro

The Jeep Liberty (KJ/KK), or Jeep Cherokee (KJ/KK) outside North America, is a compact SUV produced by the Jeep marque of Chrysler. It was introduced for 2002 with styling inspired by the Dakar^[1] and Jeepster^[2] concept cars. The Liberty, nominated for the North American Truck of the Year award for 2002, was intended as a replacement for the discontinued Jeep Cherokee (XJ). The Liberty sits in size between the Patriot/Compass and Grand Cherokee in Jeep's SUV lineup, but priced between the Wrangler and Grand Cherokee. It was the smallest of the 4-door Jeep SUVs up until the 4-door Compass and Patriot arrived for 2007.

70 percent of Liberty buyers are new to the Jeep marque. It is assembled at the Toledo North Assembly factory in Toledo, Ohio.

[hide]

[edit] First generation KJ (2002-2007)

First generation

Production	2002-2007
Platform	Chrysler KJ platform
Engine(s)	*2.4 L PowerTech* I4 •Displacement:144.0 CID (2,360 cc)^[3] •Stroke: 3.82 in (97 mm)^[3] •Bore: 3.46 in (88 mm)^[3] •Power: 172 hp (128 kW) 3.7 L PowerTech V6 •Displacement:226.0 CID (3,701 cc)^[4] •Stroke: 3.57 in (91 mm)^[4] •Bore: 3.66 in (93 mm)^[4] •Power: 210 hp (160 kW) 2.8 L VM Motori CRD turbo I4** •Displacement:171 CID (2,768 cc)^[5] •Stroke: 3.94 in (100 mm)^[5] •Bore: 3.70 in (94 mm)^[5] •Power: 160 hp (120 kW)^[5] •Torque: 295 ft·lbf (400 N·m)^[5]
Transmission(s)	5-speed NVG NV1500 manual 5-speed NVG NV3500 manual 6-speed NVG NSG370 manual 4-speed Chrysler 42RLE automatic 5-speed Mercedes W5A400 Transmission (CRD only)
Wheelbase	104.2 in (2647 mm)
Length	2005-07: 174.7 in (4437 mm) 2002-04: 174.2 in (4425 mm)
Width	2002-04: 71.1 in (1806 mm) 2005-07: 71.8 in (1824 mm)
Height	2002-04: 73.2 in (1860 mm) 2005-07: 69.8 in (1773 mm)
Curb weight	4033 lb (1829 kg)

Three trim levels were offered for the Jeep Liberty: the top end Limited, a more rugged looking Renegade, or the base Sport. All are available with either 2WD or 4WD. In 2007, the Renegade trim level was replaced with the Latitude that appears to focus on a more urban appearance.

The Liberty was the first Jeep to use two new PowerTech engines, the 150 hp 2.4 L I4, dropped in 2006, and the 210 hp 3.7 L V6. A VM Motori 2.8 L I4 common rail turbo diesel became available in CRD branded 2005-2006 Sport and Limited models. The diesel utilized a variable geometry turbocharger and generated 160 horsepower (120 kW) and 295 pound-feet of torque. The overbuilt nature of the diesel powerplant added nearly 200 pounds to the CRD's curb weight versus the gasoline model. DaimlerChrysler introduced the CRD to gauge the marketability of diesel engines in North America; diesels are already common in Europe. Jeep exceeded their expectations by selling 10,000 Liberty CRD models in the first calendar year of sales.

Only available in 2005 and 2006 for the Sport and Limited models, the 2.8L VM Motori CRD has since been discontinued due to stricter 2007 United States diesel emission standards. Maine, Vermont, Massachusetts, New York, and California had already banned sale of the vehicle due to their rigid state emissions regulations. A 3.0L CRD engine, based on a Mercedes-Benz BlueTec design, is still in production for the Jeep Grand Cherokee.

The Liberty was not the first Jeep vehicle to use an independent front suspension, as the Jeep Wagoneer first used it in the 1960s. The Jeep Wagoneer with the independent front suspension was never put into production, due to how fast the bushings would wear out.

[edit] Four Wheel Drive Systems

The Liberty is available with either a part time Command-Trac or full time Selec-Trac transfer case. The Command-Trac transfer case has four positions: 2-HI, 4-HI, Neutral, and 4-LO. The lever is placed in 2WD HI for regular driving, this allows the two rear tires to receive power. The second position, 4WD HI, is used for driving on slippery or loose pavement. This position locks both the front and rear drive shafts together splitting engine power equally between all four tires. The third position, Neutral, disengages both drive shafts from the transfer case allowing the car to roll freely; this is used for towing behind another vehicle, for example. The last position, 4WD LO is used for situations in which there is very little traction. This position, like 4WD HI locks both the front and rear drive shafts together, and by using a lower gear ratio, allows for 2.72 times more torque (however, the speed is limited to around 25 MPH max). It should be noted that using 4WD HI or LO on dry pavement is hazardous to vehicle components, through drive line binding and wheel-hop.

The Selec-Trac transfer case has five positions: 2-HI, 4-HI Part-Time, 4-HI Full-Time, Neutral, and 4-LO. This transfer case is different from the Command-Trac transfer only in the extra 4WD HI Full-Time position. The 4WD HI Full-Time position adds the same traction benefits that the part-time 4WD setting offers, but features an open differential between the front and rear axles to allow the two axles to spin at independent speeds and eliminate drive line binding and wheel-hop. This position gives the rear wheels 60% of the engine's power and the front wheels 40% of the engine's power. The division of power and open center differential allows the Selec-Trac transfer case to be theoretically operated at all times in an "All Wheel Drive" mode with no adverse effects.

[edit] International versions

Numerous versions are available in markets outside of the U.S. and Canada.

A commercial Cherokee version with 2.5 CRD engine and five-speed transmission rated at 34.4 mpg–imp (8.21 L/100 km / 28.6 mpg–U.S.) has a completely flat cargo area (the rear seat area has a carpeted full-length galvanized metal floor) and the rear quarter glass and rear door glass is replaced with fixed body colored aluminium panels (the front doors have power windows). For additional cargo security a removable floor to ceiling metal and mesh bulkhead is optional. In European markets, VAT registered buyers can claim back the tax paid as this qualifies as a Commercial Vehicle.

Arab American Vehicles Company (a joint venture) assembles the Jeep Cherokee (Liberty) for the Egyptian market.
Carabobo Assembly Plant (DaimlerChrysler de Venezuela) assembles the Jeep Cherokee (Liberty) in Valencia, Carabobo for the Venezuelan market.

[edit] Second generation KK (2008-present)

Second generation

Production	2008-present
Platform	Chrysler KK platform
Engine(s)	*3.7 L PowerTech* V6** •Displacement:226.0 CID (3,701 cc)^[4] •Stroke: 3.57 in (91 mm)^[4] •Bore: 3.66 in (93 mm)^[4] •Power: 210 hp (160 kW)
Transmission(s)	4-speed automatic 6-speed manual
Wheelbase	106.1 in (2695 mm)
Length	176.9 in (4493 mm)
Width	72.4 in (1840 mm)
Height	70.1 in (1780 mm)
Related	Dodge Nitro

The Jeep Liberty received a complete redesign for the 2008 model year with a more boxy and off-road look, like that of the 2007 Dodge Nitro, which is built on the same platform (The Liberty continues essentially identical powertrain as the old Liberty's^[6], while the Nitro is not offered with low-range gearing). The 2008 Liberty debuted at the 2007 New York International Auto Show.^[7]

The Liberty has dropped its four-cylinder option because of the Patriot and Compass crossover SUVs taking its place as Jeep's four-cylinder vehicles. The iron-block, aluminum-head V6 is the only engine for 2008. Towing capacity is 5000 pounds. For now, there is no diesel model for the U.S. Jeep stopped building the Liberty CRD for the American market because it could not meet tougher 2007 emissions standards. Transmission choices are both carry-overs: a six-speed manual or a four-speed automatic. Standard equipment includes electronic stability control with roll mitigation, traction control, and anti-lock brakes with brake assist. New Features include standard are side airbags and optional features are rain-sensing wipers. Sirius Satellite Radio, Bluetooth, a navigation system, and the MyGig entertainment system, complete with a 20GB hard drive, are options.

Two models will be offered at rollout: Sport and Limited. Wheel choices are 16-, 17- and 18-inch (460 mm). Among the more distinctive features is the Sky Slider, a power roof made from “reinforced acrylic cloth” that opens over the front and rear seats. The Sky Slider opens up to 60inches by 30 inches (760 mm), or 5 ft (1.5 m) by 2.5 ft (0.76 m), which is the largest opening in its class. Jeep claims that the idea behind the Sky Slider was to give consumers the open-air feeling from previous Jeep models while maintaining the rigidity and safety of a sturdy frame.^[8]

Jeep Cherokee

2008-08-03T16:57:00.000+08:00

From Wikipedia, the free encyclopedia

(Redirected from Jeep Cherokee Sport)

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See also Jeep Cherokee for other models using this name

Jeep Cherokee (XJ)

Manufacturer	American Motors (AMC) Chrysler Corporation DaimlerChrysler
Production	1984–2001 (USA) 1984–2005 (China)
Assembly	Toledo, Ohio Beijing, China
Successor	Jeep Liberty
Class	Compact SUV
Body style(s)	2-door SUV 4-door SUV
Layout	Front-engine, rear-wheel drive / Four-wheel drive
Engine(s)	2.5 L AMC 150 I4 2.8 L GM 60° LR2 V6 2.1 L Renault diesel I4 4.0 L AMC 242 I6 4.0 L AMC 242 H.O. I6 4.0 L 242 Power Tech I6 2.5 L VM Motori diesel I4
Transmission(s)	4-speed Aisin AX-4 manual 4-speed Borg-Warner T-4 manual 5-speed Aisin AX-5 manual 5-speed Aisin AX-15 manual 5-speed Borg-Warner T-5 manual 5-speed NVG NV3550 manual 5-speed Peugeot BA-10/5 manual 3-speed Chrysler A904 automatic 3-speed 30RH automatic 4-speed Aisin AW-4 automatic
Wheelbase	101.4 in (2576 mm)
Length	1987-1990: 165.3 in (4199 mm) 1991-93: 168.8 in (4288 mm) 1994-96: 166.9 in (4239 mm) 1997-2001: 167.5 in (4255 mm)
Width	1987-1993: 70.5 in (1791 mm) 1994-96: 67.7 in (1720 mm) 1997-99: 67.9 in (1725 mm) 2000-01: 69.4 in (1763 mm)
Height	1987-88 2WD: 63.4 in (1610 mm) 1987-1993: 63.3 in (1608 mm) 1994-99 2WD: 63.9 in (1623 mm) 1994-2001 4WD: 64.0 in (1626 mm) 2000-01 2WD: 63.8 in (1621 mm)
Curb weight	3057 lb (1387 kg) (approx.)

The Jeep Cherokee (XJ) was a monocoque (unibody) compact SUV. It shared the name of the original full-size SJ model, but having no true pickup truck heritage, it actually set the stage for the modern SUV. Its innovative appearance and sales popularity spawned important imitators as other automakers began to notice that this model began replacing regular cars.^[1] It was built in Toledo, Ohio in the United States and in Beijing, China. The XJ platform provided the mechanical basis for the MJ-series Jeep Comanche pick-up.

The XJ was selected by Robert Cumerford as one of the 20 greatest cars of all time, calling it "possibly the best SUV shape of all time, it is the paradigmatic model to which other designers have since aspired."^[2]

1984-1996

1984-1990 Jeep Wagoneer (XJ platform)

1993-1996 Jeep Cherokee XJ (Right hand drive)

The XJ Cherokee was introduced in 1984 as the first unibody Jeep. Designs of the XJ Cherokee date back to 1978 when a team of American Motors (AMC) and Renault engineers drew several sketches. A few clay models were based on the existing SJ Cherokee. Early sketches of the XJ Cherokee had an European influence, and most of the styling cues were done by AMC engineers. The ongoing debate suggests that Renault sketch artists were involved right after the 1979 partnership with AMC.^{[citation needed]} Noticing that General Motors was developing a new two-door S-10 based Blazer, AMC decided to design an entirely new four-door model, but worried about rollovers Gerald C. Meyers hired one of Ford's best engineers, Roy Lunn to design what is known as the Quadra-Link suspension.^[3] François Castaing developed the drivetrain using a much smaller engine than normally found in 4WD vehicles and reduced the weight of the new model,^[4]

Both two- and four-door versions of the XJ Cherokee were offered throughout its lifetime, each having exactly the same track and wheelbase measurements. Two-door models, however, received longer doors and front seats that could fold forward to assist in rear passenger entry and exit. This was in addition to extended-length rear windows that did not open, although an optional rear vent window was available on some models. Its appearance has led some to mistakenly believe that the two-door models are a short wheelbase version of the four-door.

A variation on the Cherokee from 1984 through 1990 was the Jeep Wagoneer. It was sold in two trim levels: the Wagoneer and the Wagoneer Limited. Both Wagoneers were distinguished from the Cherokee by the four headlights. The Wagoneer Limited came with vinyl wood trim on the sides.

This version was the first to be sold in Europe; it was launched in 1992 in some markets, 1993 for the United Kingdom. Early versions had the 4.0 L (242 CID) six-cylinder engine only: the 2.5 L (150 CID) engine did not arrive in Europe until 1995.

American Motors's compact XJ Cherokee was to be replaced by a new and larger model known as the XJC (later named the Jeep Grand Cherokee when introduced in 1993) that was under development by AMC.^[5] However, the smaller model's continuing popularity caused Chrysler executives, as the new owners of AMC, to rethink this decision. The Jeep XJ has remained a popular choice by off-roading enthusiasts due to its potent off-roading capability in stock form. Its popularity has resulted in strong ongoing aftermarket support in the form of a wide variety of products and upgrade availability.

1997-2001

1997-2001 Cherokee Sport 4-door

After 13 years of production, 1997 saw the Cherokee receive updated exterior and interior styling. Both the two- and four-door bodies remained in production, receiving a steel tailgate (replacing the fiberglass one used previously),a new taillight design, additional plastic molding along the doors, as well as a new front header panel that featured more aerodynamic styling; the interior was similarly updated with an all-new design and instruments, and a stiffer unibody frame brought improvements to Noise, Vibration, and Harshness measurements. Both the 4- and 6-cylinder engines were offered through the 2000 model year, though only the straight-six was available in 2001. For the 2000 and 2001 model years, all six-cylinder XJs received a distributorless ignition system using coil-on-plug ignition replacing the 'traditional' system previously used; coupled with better exhaust and intake porting, this gave a minor increase in power over the previous models. Transmission, axle, and transfer case choices were carried over from the previous models.

The Jeep Liberty (KJ) was already a done deal to replace the Cherokee, but in a quote from Brandweek: one of the first moves Wolfgang Bernhard made when he came to Chrysler in 2000 was to help kill the XJ Cherokee.^[6] Thus, the (XJ) Cherokee line was replaced in 2002 by the Jeep Liberty (KJ), although it is called the "Cherokee" in most foreign markets. When (XJ) Cherokee production ended in mid 2001, the portion of the Toledo South Assembly Plant devoted to its production was slowly torn down.

TOYOTA PRIUS

2008-07-29T19:08:00.000+08:00

The Toyota Prius [ˈpri.əs] is a hybrid electric mid-size car developed and manufactured by the Toyota Motor Corporation.

The Prius first went on sale in Japan in 1997, making it the first mass-produced hybrid vehicle. It was subsequently introduced worldwide in 2001. The Prius is sold in more than 40 countries and regions, with its largest markets being those of Japan and North America.^[1]

According to the United States Environmental Protection Agency, the 2008 Prius is the most fuel efficient car sold in the U.S.^[2].

According to the UK Department for Transport, the Prius is tied as the third least CO₂-emitting vehicle on sale in the UK,^[3] and there are eight cars which are more fuel-efficient than it for the combined use cycle.

Current 2004–present (model NHW20)

NHW20

Production	2004–2008
Assembly	Tsutsumi, Japan (Toyota City) Kariya, Aichi, Japan Blue Springs, Mississippi (beginning in fall 2010)
Class	Midsize car
Body style(s)	5-door hatchback
Engine(s)	Toyota Hybrid System II Gasoline: 1.5 L DOHC I4 VVT-i 57 kW (76 hp) @ 5000 rpm 115 N·m (85 ft·lbf) @ 4200 rpm Electric: 500 V 50 kW (67 hp) @ 1200 rpm 400 N·m (295 ft·lbf) @ 0 rpm AT-PZEV Net power: 110 hp (82 kW)
Transmission(s)	1-speed planetary gear
Wheelbase	2700 mm (106.3 in)
Length	4450 mm (175.33 in)
Width	1725 mm (67.97 in)
Height	1490 mm (58.71 in)
Curb weight	1325 kg (2921 lb)

The Prius is completely redesigned into a mid-size liftback which is between the Corolla and the Camry in size. The new model is 6 inches (150 mm) longer than the previous version.^[4] Its more aerodynamic body resulted in a drag coefficient of 0.26.^[5]

The new Hybrid Synergy Drive (HSD) uses an all-electric compressor for cooling. Combined with a smaller and lighter NiMH battery, the NHW20 is more powerful and more efficient than the NHW11.^[6] Air conditioning is now operated independently of the gasoline engine, an industry first.^[7] In the U.S., the battery pack of the 2004 Prius is warranted for 100,000 miles (160,000 km) or 8 years, although Toyota has stated that they expect it to last 15 years. The warranty is instead 150,000 miles (240,000 km) or 10 years^[8] for Prius in California, and in the seven Northeastern states that have adopted the stricter California emission control standards.

It is classified as a SULEV (Super Ultra Low Emissions Vehicle and is certified by California Air Resources Board as an "Advanced Technology Partial Zero Emission Vehicle" (AT-PZEV).^[9]

NHTSA (United States) crash testing of the 2004 Prius yielded a five star driver and four star passenger rating in the frontal collision test (out of five stars). Side crash results were four out of five stars for both front and rear seats. The car scored four out of five stars in rollover testing.^[10]

In 2004, EuroNCAP tested the Prius. It earned the following ratings: Adult Occupant: Child Occupant: Pedestrian: .^[11]

2006 Prius cut-away in Toyota showroom in Paris

Among the Prius' options are Toyota's implementation of an advanced key called Smart Key System or SKS (the feature can be user-deactivated), DVD navigation on the MFD, vehicle stability control and Bluetooth for hands-free calling. The 2006 model introduced some minor cosmetic changes, such as a higher-resolution liquid crystal display, as well as new optional features such as a rear-view camera, advanced airbags and an upgraded audio system with an auxiliary input. The 2007 Prius adds advanced and side-curtain airbags standard on all models. A Touring Edition was introduced that includes an elongated larger rear spoiler as well as larger, sharper-pointed 7-spoke 16" alloy wheels with plastic hub cap cover to protect it from scratches when parking against the curb. The Touring Edition also comes with a firmer European style tuned suspension, standard high-intensity-discharge (HID) headlights and integrated (non-HID) fog lights.

Automated parallel and reverse parking is available in Japan and Europe. ^[12]

Production of the Prius for the China market began in December 2005 by Sichuan FAW Toyota Motor, a joint venture with First Automobile Works.

TOYOTA

2008-07-19T07:03:00.000+08:00

In 1933, Toyoda Automatic Loom Works created a new division devoted to the production of automobiles under the direction of the founder's son, Kiichiro Toyoda. Kiichiro Toyoda had traveled to Europe and the United States in 1929 to investigate automobile production and had begun researching gasoline-powered engines in 1930.^[7] Toyoda Automatic Loom Works was encouraged to develop automobile production by the Japanese government, which needed domestic vehicle production partly due to the worldwide money shortage and partly due to the war with China.^[8] In 1934, the division produced its first Type A Engine, which was used in the first Model A1 passenger car in May 1935 and the G1 truck in August 1935. Production of the Model AA passenger car started in 1936. Early vehicles bear a striking resemblance to the Dodge Power Wagon and Chevrolet, with some parts actually interchanging with their American originals.^[8]

Although the Toyota Group is best known today for its cars, it is still in the textile business and still makes automatic looms, which are now computerized, and electric sewing machines which are available worldwide.

Toyota Motor Co. was established as an independent and separate company in 1937. Although the founding family's name is Toyoda (豊田), the company name was changed in order to signify the separation of the founders' work life from home life, to simplify the pronunciation, and to give the company a happy beginning. Toyota (トヨタ) is considered luckier than Toyoda (豊田) in Japan, where eight is regarded as a lucky number, and eight is the number of strokes it takes to write Toyota in katakana.^[9] In Chinese, the company and its vehicles are still referred to by the equivalent characters (traditional Chinese: 豐田; simplified Chinese: 丰田; pinyin: fēng tián), with Chinese reading.

During the Pacific War (World War II) the company was dedicated to truck production for the Imperial Japanese Army. Because of severe shortages in Japan, military trucks were kept as simple as possible. For example, the trucks had only one headlight on the center of the hood. The war ended shortly before a scheduled Allied bombing run on the Toyota factories in Aichi.

1957 Toyopet Crown

After the war, commercial passenger car production started in 1947 with the model SA. In 1950, a separate sales company, Toyota Motor Sales Co., was established (which lasted until July 1982). In April 1956, the Toyopet dealer chain was established. The following year, the Toyota Crown became the first Japanese car to be exported to the United States and Toyota's American and Brazilian divisions, Toyota Motor Sales Inc. and Toyota do Brasil S.A., were also established.

Toyota began to expand in the 1960s with a new research and development facility, a presence in Thailand was established, the 10 millionth model was produced, a Deming Prize and partnerships with Hino Motors and Daihatsu were also established. The first Toyota built outside Japan was in April 1963, at Port Melbourne in Australia.^[10] By the end of the decade, Toyota had established a worldwide presence, as the company had exported its one-millionth unit.

With high gas prices and a weak US economy in the summer of 2008, Toyota reported a double-digit decline in sales for the month of June, similar to figures reported by the Detroit Big Three. For Toyota, these were attributed mainly to slow sales of its Tundra pickup, as well as shortages of its fuel-efficient vehicles such as the Prius, Corolla and Yaris. In response, the company has announced plans to idle its truck plants, while shifting production at other facilities to manufacture in-demand vehicles.

DSP

2008-07-13T08:21:00.001+08:00

Digital signal processing (DSP) is concerned with the representation of the signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing. DSP includes subfields like: audio and speech signal processing, sonar and radar signal processing, sensor array processing, spectral estimation, statistical signal processing, digital image processing, signal processing for communications, biomedical signal processing, seismic data processing, etc.

Since the goal of DSP is usually to measure or filter continuous real-world analog signals, the first step is usually to convert the signal from an analog to a digital form, by using an analog to digital converter. Often, the required output signal is another analog output signal, which requires a digital to analog converter.

DSP algorithms have long been run on standard computers, on specialized processors called digital signal processors (DSPs), or on purpose-built hardware such as application-specific integrated circuit (ASICs). Today there are additional technologies used for digital signal processing including more powerful general purpose microprocessors, field-programmable gate arrays (FPGAs), digital signal controllers (mostly for industrial apps such as motor control), and stream processors, among others.

Kenwood TS-2000

2008-07-07T19:37:00.001+08:00

Variations

TS-2000, the standard base station model, with the regional versions
- K-Type for the Americas;
- E-Type for Europe;
- E2-Type for Spain;
TS-2000X, same as the above with the addition 1.2 GHz or 23 cm capability;
TS-B2000, a sleek "black box" unit requiring a computer or an optional mobile control panel for control
TS-2000LE, limited production TS-2000 with a black finish to celebrate Kenwood's 60th Anniversary

Features

The TS-2000 is a feature-rich transceiver designed to appeal to users who want a high amount of capability and versatility in a single radio. As an "all-band" transceiver, the TS-2000 offers a maximum power output of 100 watts on the HF, 6 meters, and 2 meters bands, 50 watts on 70 centimeters, and, with the TS-2000X or the optional UT-20, 10 watts on the 1.2 GHz or 23 centimeters band. The (American version) radio's main receiver covers 30 kHz through 60 MHz, 142 MHz through 152 MHz, and 420 through 450 MHz (plus 1240 through 1300 MHz with the "X" model). The sub-receiver tunes between 118 and 174 MHz, and from 220 to 512 MHz (VFO ranges). [2]

On the radio's main receiver, Kenwood chose to use DSP at the IF level, so a very flexible selection of bandwidths are available without the purchase of mechanical filters, as was necessary on past radios. Users can adjust the low-cut and high-cut frequencies to arrive at the desired bandwidth.

Some of the more novel features are backlit keys, a built-in TNC for receiving DX Packet Cluster information, and the Sky Command II+ system (found on the K-Model), which allows for remote control of the transceiver using Kenwood's TH-D7A handheld or TM-D7000A mobile radio.

Some users have complained of a "noisy receiver" on the high frequency portion of the radio. This has tended to be disputed between various reviews on the eham.net site. Though there has been a modification developed that addresses this issue, it involves the replacement of 24 band switching diodes.

Kenwood TS-2000

2008-06-27T08:43:00.000+08:00

The Kenwood TS-2000 is an amateur radio transceiver manufactured by Kenwood Electronics. Introduced in the year 2000, the radio has come to be very popular among hams for its "all-in-one" functionality. It can transmit on all amateur radio bands between 160 meters and 70 centimeters, with the exception of the 1.25 meters band, and the "X" model also has built-in 23 centimeters band capability (which can be added to other models after purchase as an accessory).

As of May 2008, the TS-2000 is the second most reviewed HF transceiver on the popular Product Review section of eHam [1], with 387 reviews and an average rating of 4.5 (out of 5), second only to the IC-706 line of radios from ICOM, with 360.

Amateur radio transceivers

2008-06-21T22:49:00.000+08:00

Kenwood has offered distinct lines of HF, VHF/UHF, and portable amateur radio models.
Among the product lines, the "TS" series of HF transceivers can be said to be among Kenwood's flagship products. These radios cover the HF ("high frequency") bands, from 1.8 to 30 MHz, and can easily let the user communicate around the world, via voice, CW (Morse), PSK31 or RTTY (digital modes of communication), with output power of around 50-100 Watts. These included:
TS-800 series -- From the late 1970s, the TS-820 was one of the first Kenwood transceivers to gain widespread acceptance in the Amateur Radio community. The original model included a single VFO (variable frequency oscillator), although a second VFO could be purchased as a stand-alone option; a matching receiver, the R-820, was also available, which permitted split frequency operation. A digital display was another option, available to be retrofit to the original device. With the digital display installed, a TS-820 could be named a "TS-820S": all future Kenwood HF transceivers have used the "S" designation to signify presence of a digital display, though the feature has long since become standard equipment.
TS-900 series -- From the mid-1980s, the TS-930S and, to a greater extent, the TS-940S represented a step-up in features, size, and cost from the 800-series models. Introduced around 1986, the TS-940S was considered a classic of its time which was later succeeded by the TS-950. It was Kenwood's first model to permit the HF transceiver to be fully controlled by a personal computer (via RS-232 cable and an aftermarket interface, the IF-232). In later years, this became standard equipment on almost all serious HF radios, and some radios would drop the human interface features entirely, being controlled entirely by a remote computer.
TS-400 series -- with models including the TS-430S, TS-440S, TS-450 and TS-480, these units featured a smaller size, were operated on 12 Volts -- meaning batteries could be used -- and were suitable for use as a portable base station, such as during Amateur Radio Field Day.
TS-600 series -- These models were mainly identical to their 400 series counterparts but offered the 6 Meters band as an addition. For example the TS-450S and the TS-690S have the same exterior and mostly the same specifications on the 1.8-30 MHz HF bands, but adding the 6 Meters band.
Other series include the 100, 500, and the new 2000 series. The TS-2000 is Kenwood's current top of the line model. It includes all-mode operation on HF, 6 meters, 2 meters, 70 centimeters (420 - 450 MHz), and in the "X" model the 23 centimeters band (1.24 - 1.30 GHz). Kenwood also offers a "B" model which is a transceiver without display or controls and is completely controlled by a remote computer or a separate control unit. This allows using it as a mobile transceiver where the main unit is placed in the trunk or an area that provides enough room to house it, possibly closer to the antenna, and have a control unit in the front of the car. A setup like this allows the control unit to be placed closer to the driver and the transceiver closer to the antenna which shortens the cable, reducing possible interference.

AMATEUR RADIO OPERATOR

2008-06-14T21:13:00.000+08:00

An amateur radio operator is an individual who typically uses equipment at an amateur radio station to engage in two-way personal communications with other similar individuals on radio frequencies assigned to the amateur radio service. Most amateur radio operators have been granted an amateur radio license by a governmental regulatory authority. As a component of their license, most amateur radio operators are assigned a call sign that they use to identify themselves during communication. There are about three million amateur radio operators worldwide.[1]
Amateur radio operators are also known as radio amateurs or hams. The term 'ham' as a nickname for amateur radio operators originated in a pejorative usage by operators in commercial and professional radio communities. The word was subsequently welcomed by amateur radio operators, and it stuck. An amateur radio operator who has died is referred to by other amateur radio operators as a "silent key", and the suffix /SK is appended to his or her callsign.

HIGH FREQUENCY

2008-06-14T21:05:00.000+08:00

High frequency (HF) radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters (ten to one hundred metres). Frequencies immediately below HF are denoted Medium-frequency (MF), and the next higher frequencies are known as Very high frequency (VHF). Shortwave (2.310 - 25.820 MHz) overlaps and is slightly lower than HF.

AMATEUR RADIO HISTORY

2008-06-14T18:08:00.000+08:00

Though its origins can be traced to at least the late 1800s, amateur radio, as practiced today, began in the 1920s. As with radio in general, the birth of amateur radio was strongly associated with various amateur experimenters and hobbyists. Throughout its history, amateur radio enthusiasts have made significant contributions to science, engineering, industry, and social services. Research by amateur radio operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency.

Microphone

2008-06-12T05:53:00.000+08:00

Penggunaan microphone disarankan menyesuaikan dengan selera sehingga mendapatkan suara yang diinginkan.....

SETTING

2008-05-25T20:04:00.000+08:00

Setiap accesories perlu setting ? kalau ada yang mau sharing untuk setting silahkan..... misalnya setting untuk Feedback Destroyer Pro (DSP1124P) dst.... oke

Equipment & Accesories

2008-05-25T07:47:00.000+08:00

Radio yang digunakan adalah radio yang sederhana yaitu JRC-JST 245 atau Icom IC 751 dengan Accesories yang digunakan semua dari produk BEHRINGER :
1. Microphone B1
2. Ultragain Pro (MIC2200) --preamp
3. Feedback Destroyer Pro (DSP1124P)
4. Autocom Pro-XL (MDX1600)
5. Virtualizer Pro (DSP2024P)
6. Ultrafex Pro (EX3200)
7. Mixer Eurorack Ub 1002 Fx
8. Ultralink Pro (MX882)
9. Ultra DI-100

de yb7hx

yb7hx radio station

2008-04-30T13:58:00.000+08:00

ic 751 bisa juga disuntik dan menghasilkan audio dungdung

yb7hx with audio dungdung

Yaesu FT-2000

Heil Sound PR 40 Microphone

Kenwood TS-2000/B2000/2000x

Amateur radio

Antenna (radio)

Terminology

Overview

Parameters

Resonant frequency

Gain

Radiation pattern

Impedance

Efficiency

Bandwidth

Polarization

Transmission and reception

Basic antenna models

Practical antennas

Effect of ground

Mutual impedance and interaction between antennas

Antenna gallery

Antennas and antenna arrays

Antennas and supporting structures

Diagrams as part of a system

[

Jeep Liberty

Contents

[edit] First generation KJ (2002-2007)

[edit] Four Wheel Drive Systems

[edit] International versions

[edit] Second generation KK (2008-present)

Jeep Cherokee

From Wikipedia, the free encyclopedia

1984-1996

1997-2001

TOYOTA PRIUS

Current 2004–present (model NHW20)

TOYOTA

DSP

Kenwood TS-2000

Variations

Features

Kenwood TS-2000

Amateur radio transceivers

AMATEUR RADIO OPERATOR

HIGH FREQUENCY

AMATEUR RADIO HISTORY

Microphone

SETTING

Equipment & Accesories

yb7hx radio station